• Title, Summary, Keyword: 가역성

Search Result 356, Processing Time 0.047 seconds

An Analysis On Students' Misconceptions of the Reversibility of Irrational Functions (무리함수의 가역성에 대한 학생들의 오개념 분석)

  • Lee, Ki-Suk;Lee, Du-Ho
    • Communications of Mathematical Education
    • /
    • v.24 no.3
    • /
    • pp.709-730
    • /
    • 2010
  • The inverse function of a one-to-one correspondence is explained with a graph, a numerical formula or other useful expressions. The purpose of this paper is to know how low achieving students understand the learning contents needed reversible thinking about irrational functions. Low achieving students in this study took paper-pencil test and their written answers were collected. They made various mistakes in solving problems. Their error types were grouped into several classes and identified in this analysis. Most students did not connected concepts that they learned in the lower achieving students to think in reverse order in case of and to visualize concepts of functions. This paper implies that it is very important to take into account students' accommodation and reversible thinking activity.

Validity of Peak Expiratory Flow for Assessing Reversible Airflow Obstruction (기류 가역성 평가에 있어서 최대호기유속 측정의 유용성)

  • Chol, Won-Il;Kwak, Jin-Ho;Kwon, Doo-Young;Han, Seung-Beom;Jeon, Young-June
    • Tuberculosis and Respiratory Diseases
    • /
    • v.48 no.4
    • /
    • pp.522-529
    • /
    • 2000
  • Backgrounds : Assessment of the presence and degree of reversibility of airflow obstruction is clinically important in patients with asthma or chronic obstructive pulmonary disease. The measurement of peak expiratory flow(PEF) is a simple, fast, and cheap method to assess the severity of obstruction and its degree of reversibility. Assessing the reversibility of airflow obstruction by peak expiratory flow(PEF) measurements is practicable in general practice, but its usefulness has not been well investigated. We compared PEF and $FEV_1$ in assessing reversibility of airflow obstruction in patients with chronic obstructive pulmonary disease or asthma and developed a practical criterion for assessing the presence of reversibility in general practice. Methods : PEF measurements were performed (Spirometry) in 80 patients(aged 24-78) with a history of asthma or chronic obstructive lung disease before and after the inhalation of 200 g salbutamol. The change in PEF was compared with the change in forced expiratory volume in one second($FEV_1$). Reversible airflow obstruction was analyzed according to American Thoracic Society(ATS) criteria. Results : A 12% increase above the prebronchodilator value and a 200ml increase in either FVC or $FEV_1$ reversibility were observed in 45%(36) of the patients. Relative operating characteristic(ROC) analysis showed that an absolute improvement in PEF of 30 l/min gave optimal discrimination between patients with reversible and irreversible airflow obstruction(the sensitivity and specificity of an increase of 30 l/min in detecting a 12% increase above the prebronchodilator value and a 200ml increase in either FVC or $FEV_1$ were 72.2% and 72.7% respectively, with a positive predictive value of 68.4%). Conclusions : Absolute changes in PEF can be used to diagnose reversible airflow obstruction.

  • PDF

The Flesh Encountering with the Others (살과 타자의 만남)

  • Ryu, Eui-Geun
    • Journal of Korean Philosophical Society
    • /
    • v.105
    • /
    • pp.193-214
    • /
    • 2008
  • This paper is about to analyse Merleau-Ponty's notion of flesh on textual evidences through the structure of perception and to apply this result to his theory of the others. In the first place, we study what he thinks of philosophical investigation and thus of the essence of philosophy. With this process, we find out that perception is more important than reflection in philosophical investigation. Differently from the objective or objectivistic viewpoint, the truth of perception is revealed to go beyond distinction between consciousness and object. This truth refers to reversibility which Merleau-Ponty thinks to be the ultimate truth. The reversibility of perception leads to chiasms which reveal and unreveal the beings. In the final analysis, the flesh as reversibility is the Being in the beings. When it comes to the problem of other minds, we are confirmed through the movement of flesh that self-presence is the presence to the differentiated world, namely the others.

A Study on the Information Reversibility of Quantum Logic Circuits (양자 논리회로의 정보 가역성에 대한 고찰)

  • Park, Dong-Young
    • The Journal of the Korea institute of electronic communication sciences
    • /
    • v.12 no.1
    • /
    • pp.189-194
    • /
    • 2017
  • The reversibility of a quantum logic circuit can be realized when two reversible conditions of information reversible and energy reversible circuits are satisfied. In this paper, we have modeled the computation cycle required to recover the information reversibility from the multivalued quantum logic to the original state. For modeling, we used a function embedding method that uses a unitary switch as an arithmetic exponentiation switch. In the quantum logic circuit, if the adjoint gate pair is symmetric, the unitary switch function shows the balance function characteristic, and it takes 1 cycle operation to recover the original information reversibility. Conversely, if it is an asymmetric structure, it takes two cycle operations by the constant function. In this paper, we show that the problem of 2-cycle restoration according to the asymmetric structure when the hybrid MCT gate is realized with the ternary M-S gate can be solved by equivalent conversion of the asymmetric gate to the gate of the symmetric structure.

Role of Bronchodilator Reversibility Testing in Differentiating Asthma From COPD (만성폐쇄성폐질환과 천식을 감별 진단하는데 기관지확장제 가역성 검사의 역할)

  • Oh, Yeon-Mok;Lim, Chae Man;Shim, Tae Sun;Koh, Younsuck;Kim, Woo Sung;Kim, Dong-Soon;Kim, Won Dong;Kim, Se Kyu;Yoo, Jee Hong;Lee, Sang Do
    • Tuberculosis and Respiratory Diseases
    • /
    • v.57 no.5
    • /
    • pp.419-424
    • /
    • 2004
  • Background : Although bronchodilator reversibility testing is widely performed to diagnose asthma or COPD, there is debate upon its usefulness and methods to differentiate asthma from COPD. The purpose of this study is to elucidate the role of bronchodilator reversibility testing in differentiating asthma from COPD and to confirm which method is better at evaluating bronchodilator reversibility. Methods : 26 asthma patients and 31 COPD patients were reviewed retrospectively. Spirometry was performed before and after bronchodilator inhalation to get $FEV_1$, FVC. To evaluate bronchodilator reversibility, the increase in $FEV_1$ or FVC was expressed as three methods, 'percentage of the baseline value', 'percentage of the predicted value', or 'absolute value'. Area under the ROC curve was measured to compare the three methods. In addition, the criteria of American Thoracic Society (ATS) for bronchodilator reversibility were compared to those of European Respiratory Society (ERS). Results : 1. In differentiating asthma from COPD, 'percentage of the predicted value', or 'absolute value' method was useful but 'percentage of the baseline value' was not. However, the ability to differentiate was weak because areas under the ROC curves by all methods were less than 0.75. 2. The criteria of ERS were superior to those of ATS for bronchodilator reversibility to differentiate asthma from COPD because likelihood ratio (LR) of a positive test by ERS criteria was greater than ATS criteria and because LR of a negative test by ERS criteria was less than ATS criteria. Conclusion : In differentiating asthma from COPD, bronchodilator reversibility testing has a weak role and should be considered as an adjunctive test.

The Development of the Unfading Polyvinyl Butyral Gap-filling Material Based on Reversible Properties and Restoration of a Punchong Plate from Sam-cheon Temple Site with This Polyvinyl Butyral Product (가역성을 갖는 무황변 Polyvinyl Butyral 메움제의 개발과 이를 이용한 삼천사지 분청사기접시의 복원)

  • Han, Won-Sik;Wi, Koang-Chul;Park, Gi-Jung;Hong, Tae-Kee
    • Journal of Conservation Science
    • /
    • v.25 no.3
    • /
    • pp.293-298
    • /
    • 2009
  • We fabricated the gap-filling material for antic-ceramics restoration which were made up polyvinyl butyral (butvar) base and silane system additive in iso-propyl solvent. This was made hardness control possible that user want. And it have very strong adhesion and shear strength properties and is shown the best properties for pigment filling, anti-contractibility, coloring as like epoxy system materials. Particularly, the yellowing and ir-reversibility problem in Epoxy restoration material were finally steadiness. So, there is guarantee in the eternity and stabilization of restoration for antic-celamics. And in order to show the reversible state of the restoration, we successfully dissolve this polyvinyl butyral gap-filling materials in solvent after perfect restoring the Punchong plate from sam-chun temple site subsequently.

  • PDF

The Development of the Unfading Urethane Polymer Based on Reversible Properties for Ceramics and Restoration with This Urethane Product (가역성을 갖는 도자기 복원용 무황변 우레탄 수지의 개발과 이를 이용한 도자기의 복원)

  • Han, Won-Sik;Park, Gi-Jung;Lim, Sung-Jin;Lee, Young-Hoon;Hong, Tae-Kee;Wi, Koang-Chul
    • Journal of Conservation Science
    • /
    • v.26 no.2
    • /
    • pp.183-190
    • /
    • 2010
  • We fabricated urethane material based on properties of reversible and unfading for antic-ceramics restoration. This material with low viscosity was made hardness control possible that user want. And it have very strong adhesion and shear strength properties and is shown the best properties for pigment filling, anti-contractibility, coloring as like epoxy system materials. Particularly, the yellowing and ir-reversibility problem in epoxy restoration material were finally solved. So, there is guarantee in the eternity and stabilization of restoration for antic-celamics. And in order to show the reversible state of the restoration, we successfully dissolve this urethane materials in solvent after perfect restoring subsequently.

Nonlinear Forecasting of Daily Runoff Using Inverse Approach Method (가역접근법을 이용한 일유출량 자료의 비선형 예측)

  • Jeong, Dong Kug;Lee, Bae Sung
    • Proceedings of the Korea Water Resources Association Conference
    • /
    • /
    • pp.1178-1182
    • /
    • 2004
  • 시계열 자료의 분석과 예측은 수문학분야에서 매우 중요하면, 최근 들어 특정한 수문시계열에서 카오스 특성이 발견되고 있다. 카오스 특성을 갖는 수문시계열의 예측에 있어, 기존의 거의 모든 연구는 시스템의 특성을 파악한 뒤 예측을 실시하는 표준접근법이 채택되어왔다. 그러나 Phoon 등은 시스템의 특성분석에 앞서 예측을 실시하고, 상태공 매개변수가 시스템의 특성분석단계가 아닌 예측단계에서 평가되는 가역접근법을 제안하였다. 본 연구에서는 Phoon 등이 제안한 가역접근법과 기존에 널리 적용되어온 표준접근법을 실제 일유출량 자료에 적용함으로써, 가역접근법의 적용성을 검토하고 카오스 시계열의 특성을 파악하였다. 본 연구에서 사용한 비선형 예측 기법으로는 카오스이론이 적용된 부분근사화 기법을 이용하였다. 카오스 특성분석을 통해, Bear 강 일유출량 시계열 자료에서 카오스 특성이 나타남을 알 수 있었다. 표준접근법과 가역접근법을 이용하여 Bear 강의 일유출량 자료에 대하여 예측을 실시한 결과, 카오스 특성을 갖는 일유출량 시계열 자료의 단기 예측의 우수성을 알 수 있었으면, 가역접근법이 표준접근법에 비해 좋은 결과를 나타내었다. 특히, 가역접근법은 예측단계에서 예측시간(T)에 대하여 예측매개변수를 최적화시킴으로써 보다 정밀한 예측을 할 수 있었으며, 시스템에 대한 정보손실이 발생하였을 경우 예측에 대한 상태공간 매개변수를 다시 추정해야 하는 표준접근법에 비해 실제적 적용성이 매우 우수하였다.

  • PDF

Gate Cost Reduction Policy for Direct Irreversible-to-Reversible Mapping Method without Reversible Embedding (가역 임베딩 없는 직접적 비가역-가역회로 매핑 방법의 게이트비용 절감 방안)

  • Park, Dong-Young;Jeong, Yeon-Man
    • The Journal of the Korea institute of electronic communication sciences
    • /
    • v.9 no.11
    • /
    • pp.1233-1240
    • /
    • 2014
  • For the last three decades after the advent of the Toffoli gate in 1980, while many reversible circuit syntheses have been presented reversible embedding methods onto suitable reversible functions, only a few proposed direct irreversible-to-reversible mapping methods without reversible embedding. In this paper we present two effective policies to reduce the gate cost and complexity for the existing direct reversible mapping methods without reversible embedding. In order to develop new cost reduction policies we consider the cost influence of Toffoli module according to NOT gate arrangement in classical circuits. From this we deduced an inverse proportional property between inverting input numbers of classical AND/OR gates and reversible Toffoli module cost based on a fact - the inverting inputs of classical AND(OR) gates increase(decrease) the Toffoli module cost. We confirm the applications of the inverting input rearrangement and maximum fan-out policies preceding direct reversible mapping will be effective method to improve the reversible Toffoli module cost and complexity with the parallel using of the fan-out and supercell ones.

Reversible Image Watermarking with Differential Histogram Shifting and Error Prediction Compensation (차이값 히스토그램 쉬프팅과 오류 예측 보정을 이용한 가역 영상 워터마킹)

  • Yeo, Dong-Gyu;Lee, Hae-Yeoun;Kim, Byeong-Man;Kim, Kyung-Su
    • Journal of KIISE:Software and Applications
    • /
    • v.37 no.6
    • /
    • pp.417-429
    • /
    • 2010
  • Reversible watermarking inserts watermark into digital media in such a way that visual transparency is preserved and then enables to restore the original media from the marked one without any loss of media quality. This watermarking can be applied to quality-sensitive imaging such as medical imaging, military imaging, remote-sensing imaging, and precious artwork, where the original media should be preserved during image processing and analysis. In this paper, a reversible image watermarking technique that embeds message bits by modifying the differential histogram of adjacent pixels is presented. In order to satisfy both high embedding capacity and visual quality, the proposed technique exploits the fact that adjacent pixels in the image have highly spatial correlation. Also, we prevent overflow/underflow problem and salt-and-pepper artifacts by employing a predicted error compensation scheme. Through experiments using various test images, we prove that the presented technique provides perfect reversibility and high embedding capacity, while maintaining the induced-distortion low.